HI, yes, if you look at the bottom horizontal line it has 4 pixels (leds) with the top one (4th from the bottom) slightly less lit than the bottom 3.

That isn't supposed to be there, Actually now that I look at it some more LEDs are lit that shouldn't be (or the phone camera doesn't sync), but that bottom row is the worst case, as it makes the numbers too think...

Hm, good idea, I have another panel at the office, I'll try with that...
Also, I'll try an uno... because it worked ok with the uno, I think, but I'll loose the keyboard capabilities ;(
I think the interrupt timer or something differs from DMD and DMD2 and Uno and Leonardo.

I thought it was something more common, thank you, I'll keep you posted with what I find for future reference.

Do you need a full keyboard? If you only need to enter characters, and a full size keyboard isn't 100% needed I've used an android app on a phone to send characters via bluetooth as a solution to this. MIT App Inventor makes the app creation straightforward (and the right price) and there are heaps of examples on youtube etc for setting up a Bluetooth module to do the talking.